Recently, the number of patients suffering from glucose metabolic disorders represented by obesity and type II diabetes mellitus (hyperglycemia) has been increasing due to, for example, changes in dietary habits.
In general, the blood glucose level is increased after eating, in particular, after ingestion of a diet containing carbohydrates, and thereby insulin is secreted by pancreatic β-cells. Insulin acts on muscle, liver, adipose tissue, etc. and promotes the intake of sugar into cells, to thereby suppress an acute increase in blood glucose level after eating. If the postprandial blood glucose level remains high because of a decrease in insulin sensitivity (insulin resistance), the pancreas secretes a large amount of insulin for suppressing the increase in blood glucose level. Furthermore, if such a condition continues for a long time, the pancreas is exhausted, the secretion of insulin from the pancreatic β-cells is decreased, and, ultimately, the mechanism of insulin action does not normally function, which causes, for example, type II diabetes mellitus.
The postprandial hyperglycemia symptoms associated with insulin resistance also appears in healthy individuals not suffering from diabetes mellitus and individuals suffering from borderline diabetes mellitus. The postprandial hyperglycemia symptoms are also known to cause or exacerbate, for example, obesity, hyperlipidemia, and arteriosclerosis, in addition to type II diabetes mellitus. Accordingly, from the viewpoints of health maintenance, decrease in the risk for onset of these symptoms and diseases and prevention thereof, it is very important to prevent the postprandial hyperglycemia symptoms.
Accordingly, many materials that can suppress an acute increase in blood glucose level and secretion of insulin after eating have been developed in recent years. One example of such materials is amylase inhibitors, and an amylase inhibitor derived from wheat is used in prevention or therapy for, for example, diabetes mellitus and obesity (Non Patent Document 1).
The endosperm of wheat contains about 10 to 15% of protein. It has been reported that albumin (water-soluble protein) occupying about 11% of the protein composition has an α-amylase inhibiting activity and physiological functions such as an action of suppressing a postprandial increase in blood glucose level and an action of improving insulin resistance (Non Patent Documents 1 and 2). In particular, wheat albumin having an electrophoretic mobility of 0.19 has a high α-amylase inhibiting activity and is therefore expected to be applied to a variety of foods.
It is believed that in order to express the physiological functions of the wheat albumin, it is effective to ingest wheat albumin having an electrophoretic mobility of 0.19 (hereinafter, also may be referred to as 0.19-wheat albumin) in an amount of 125 mg or more per meal all at a time (Non Patent Document 2). As health foods having effective amounts of wheat albumin blended therein, soups and hard capsules have been marketed. In addition, Patent Document 1 discloses tablets having 0.19-wheat albumin blended therein.